writing_throttling_trigger_percentage

Description

writing_throttling_trigger_percentage specifies the upper limit of the write speed.

Limitations

• Query the parameter

  In the sys tenant or a user tenant, you can execute the SHOW PARAMETERS statement to query the parameter or query the GV$OB_PARAMETERS view for the parameter.

• Modify the parameter

  You can modify the parameter in the sys tenant or a user tenant.

Attributes

Considerations

• In OceanBase Database V4.0.0 and later, the default value of this parameter is changed to 60. This is because the throttling feature runs stably, and throttling will not be triggered in most business scenarios except upon traffic surges during data import. Even if throttling is triggered in data import, user experience is still higher than that with writing stopped. Therefore, this feature is enabled by default. To achieve smooth throttling, the default value is set to 60 instead of 80. If this parameter is set to 80, the remaining 20% of buffer must mitigate the pressure caused by the MemStore memory usage of 80%. This causes sharp throttling and greatly increases the response time of business.

• When the memory used by the MemStore reaches the threshold, the write speed limit is triggered. If this parameter is set to 100, write throttling is disabled.

Examples

Set the upper limit of the write speed to 60.

obclient> ALTER SYSTEM SET writing_throttling_trigger_percentage = 60;